CVE-2026-55603

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 79% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.5Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

http-proxy-middleware is node.js http-proxy middleware. From 3.0.4 until 3.0.7 and 4.1.1, fixRequestBody() is the library's documented helper for re-emitting a request body that was already consumed by a body parser. When the outgoing Content-Type is multipart/form-data, it rebuilds the body with handlerFormDataBodyData(), which interpolates each req.body key and value directly into the multipart wire format without neutralizing CR/LF. A \r\n inside a value (or key) lets an attacker close the current part and inject an entirely new form part. Because the proxy's own body parser saw a single opaque value, any gateway-side policy or validation performed on req.body is evaluated against a different set of fields than the upstream backend ultimately parses a request/parameter desynchronization across the trust boundary. This vulnerability is fixed in 3.0.7 and 4.1.1.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
50
EG Risk 50/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation40% × 40%
Automatability0% × 15%
EPSS PROB
0.3%
EPSS %ILE
19th
KEV
Not listed

Published

June 18, 2026

Last Modified

June 24, 2026

Advisory Details (1)

Auto-updated Jun 22, 2026
🔬 Proof of concept available. Patch available. Sources: github.
githubMentions a patch (unverified)🟡 PoC Available

multipart/form-data field injection via unescaped CRLF in `fixRequestBody` · Advisory · chimurai/http-proxy-middleware · GitHub

https://github.com/chimurai/http-proxy-middleware/security/advisories/GHSA-gcq2-9pq2-cxqm

Vendor Advisories for CVE-2026-55603(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatmta/mta-ui-rhel9:17851690132026-08-04redhat
redhatrhtas/rhtas-console-ui-rhel9:17841058942026-07-20redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFix by version rangeDependents
http-proxy-middleware—
  • 3.0.4 up to 3.0.7: fixed in 3.0.7
  • 4.0.0 up to 4.1.1: fixed in 4.1.1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 30× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 196 total refreshes for this CVE.

  1. 2026-10-10 20:00 UTCEPSS rescore
  2. 2026-10-09 20:07 UTCEPSS rescore
  3. 2026-10-08 17:12 UTCEPSS rescore
  4. 2026-10-07 23:48 UTCEPSS rescore
  5. 2026-10-06 15:18 UTCEPSS rescore
  6. 2026-10-05 17:43 UTCEPSS rescore
  7. 2026-10-04 23:22 UTCEPSS rescore
  8. 2026-10-03 14:26 UTCEPSS rescore
  9. 2026-10-03 05:09 UTCOSV refresh
  10. 2026-10-02 17:56 UTCEPSS rescore
  11. 2026-10-01 19:50 UTCEPSS rescore
  12. 2026-09-30 15:03 UTCEPSS rescore
  13. 2026-09-29 15:22 UTCEPSS rescore
  14. 2026-09-28 13:51 UTCEPSS rescore
  15. 2026-09-27 13:48 UTCEPSS rescore
  16. 2026-09-26 15:59 UTCEPSS rescore
  17. 2026-09-24 14:04 UTCEPSS rescore
  18. 2026-09-23 17:54 UTCEPSS rescore
  19. 2026-09-20 20:16 UTCEPSS rescore
  20. 2026-09-18 19:28 UTCEPSS rescore
  21. 2026-09-17 19:31 UTCEPSS rescore
  22. 2026-09-16 14:08 UTCEPSS rescore
  23. 2026-09-16 05:15 UTCEPSS rescore
  24. 2026-09-15 03:11 UTCEPSS rescore
  25. 2026-09-14 02:22 UTCEG score recompute
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  1. 2026-09-14 02:22 UTCVendor advisory
  2. 2026-09-13 16:47 UTCEPSS rescore
  3. 2026-09-13 14:00 UTCEG score recompute
  4. 2026-09-13 14:00 UTCVendor advisory
  5. 2026-09-11 14:53 UTCEPSS rescore
  6. 2026-09-10 09:35 UTCEPSS rescore
  7. 2026-09-08 22:01 UTCEPSS rescore
  8. 2026-09-07 16:01 UTCEPSS rescore
  9. 2026-09-06 13:47 UTCEPSS rescore
  10. 2026-09-04 05:06 UTCEPSS rescore
  11. 2026-09-02 14:12 UTCEPSS rescore
  12. 2026-09-01 13:54 UTCEPSS rescore
  13. 2026-09-01 04:40 UTCEPSS rescore
  14. 2026-08-30 21:11 UTCEG score recompute
  15. 2026-08-30 21:11 UTCVendor advisory
  16. 2026-08-30 19:17 UTCEPSS rescore
  17. 2026-08-30 01:22 UTCEPSS rescore
  18. 2026-08-28 21:41 UTCEPSS rescore
  19. 2026-08-27 14:25 UTCEPSS rescore
  20. 2026-08-26 14:46 UTCEPSS rescore
  21. 2026-08-25 13:49 UTCEPSS rescore
  22. 2026-08-24 22:21 UTCEG score recompute
  23. 2026-08-24 22:21 UTCVendor advisory
  24. 2026-08-24 05:13 UTCVendor advisory
  25. 2026-08-23 15:16 UTCVendor advisory
  26. 2026-08-23 03:45 UTCEG score recompute
  27. 2026-08-23 03:45 UTCVendor advisory
  28. 2026-08-23 00:19 UTCEPSS rescore
  29. 2026-08-21 23:49 UTCEPSS rescore
  30. 2026-08-21 18:53 UTCVendor advisory
  31. 2026-08-21 07:22 UTCEG score recompute
  32. 2026-08-21 07:22 UTCVendor advisory
  33. 2026-08-20 22:55 UTCEPSS rescore
  34. 2026-08-20 19:41 UTCVendor advisory
  35. 2026-08-20 08:11 UTCEG score recompute
  36. 2026-08-20 08:11 UTCVendor advisory
  37. 2026-08-19 17:04 UTCEPSS rescore
  38. 2026-08-19 08:01 UTCEG score recompute
  39. 2026-08-19 08:01 UTCVendor advisory
  40. 2026-08-18 13:48 UTCEPSS rescore
  41. 2026-08-17 13:47 UTCEPSS rescore
  42. 2026-08-17 08:17 UTCVendor advisory
  43. 2026-08-16 20:47 UTCEG score recompute
  44. 2026-08-16 20:47 UTCVendor advisory
  45. 2026-08-16 14:56 UTCEPSS rescore
  46. 2026-08-16 08:43 UTCEG score recompute
  47. 2026-08-16 08:43 UTCVendor advisory
  48. 2026-08-16 02:14 UTCEPSS rescore
  49. 2026-08-15 21:12 UTCVendor advisory
  50. 2026-08-15 09:07 UTCEG score recompute
  51. 2026-08-15 09:07 UTCVendor advisory
  52. 2026-08-15 01:30 UTCEPSS rescore
  53. 2026-08-14 20:55 UTCVendor advisory
  54. 2026-08-14 09:24 UTCEG score recompute
  55. 2026-08-14 09:24 UTCVendor advisory
  56. 2026-08-13 22:00 UTCEPSS rescore
  57. 2026-08-13 21:54 UTCVendor advisory
  58. 2026-08-13 10:23 UTCVendor advisory
  59. 2026-08-12 22:52 UTCEG score recompute
  60. 2026-08-12 22:52 UTCVendor advisory
  61. 2026-08-12 13:51 UTCEPSS rescore
  62. 2026-08-12 11:22 UTCVendor advisory
  63. 2026-08-11 23:51 UTCEG score recompute
  64. 2026-08-11 23:51 UTCVendor advisory
  65. 2026-08-11 12:20 UTCVendor advisory
  66. 2026-08-11 00:47 UTCEG score recompute
  67. 2026-08-11 00:47 UTCVendor advisory
  68. 2026-08-11 00:00 UTCEPSS rescore
  69. 2026-08-10 13:16 UTCVendor advisory
  70. 2026-08-10 01:46 UTCVendor advisory
  71. 2026-08-09 14:15 UTCEG score recompute
  72. 2026-08-09 14:15 UTCVendor advisory
  73. 2026-08-09 13:46 UTCEPSS rescore
  74. 2026-08-09 02:45 UTCEG score recompute
  75. 2026-08-09 02:45 UTCVendor advisory

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Frequently asked(5)

What is CVE-2026-55603?
CVE-2026-55603 is a high vulnerability published on June 18, 2026. http-proxy-middleware is node.js http-proxy middleware. From 3.0.4 until 3.0.7 and 4.1.1, fixRequestBody() is the library's documented helper for re-emitting a request body that was already consumed by a body parser. When the outgoing Content-Type is multipart/form-data, it rebuilds the body with…
When was CVE-2026-55603 disclosed?
CVE-2026-55603 was first published on June 18, 2026, with the most recent update on June 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55603 actively exploited?
CVE-2026-55603 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (19th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55603?
CVE-2026-55603 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55603?
A fix for CVE-2026-55603 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55603 are linked in the Vendor Advisories panel on this page.

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